Fracking in the Marcellus Shale of Pennsylvania and West Virginia do not only use millions of gallons of water per operation, according to a new report. The study also shows that operations fail to return almost all that water to its purified form.

The report, from San Jose State University, focused on water use and reporting in hydraulic fracturing in the states — and discovered that more than 90 percent of the water injected into the ground during the fracking process is lost from the hydrologic cycle.

That water is largely taken from freshwater sources. More than 80 percent of water used in West Virginia fracking operations comes from lakes and streams — in Pennsylvania, 70 percent is derived from freshwater sources.

While the Marcellus Shale formation doesn’t suffer from severe drought, other fracking sites throughout the nation do. With such vast amounts of water being taken — and never returned — the process is perpetuating concerns over drought and aquatic habitats.

“[This is relevant for] other shale basins across the U.S. where there is a bit more concern about the availability year-round, not just during times of stress,” said SJSU professor Dustin Mulvaney.